Many types of cell culture articles are constructed to provide stacked or stackable units for culturing cells. For example, T-flasks are typically made to have flat top and bottom surfaces that allow T-flasks to be stacked, providing space savings. Some modified T-flasks have multiple parallel culture surfaces within the flask to reduce time and effort associated with filling and emptying. Other culture apparatuses are multi-component assemblies having a plurality of parallel or stacked culture surfaces. With most of such stacked culture assemblies, each culture layer is isolated to reduce hydrostatic pressure on the lower culture layers. As the number of stacked layers increases, the potential effect of hydrostatic pressure increases.
Some cell culture articles are designed to operate with minimal or no headspace. For example, Corning's HYPERFlask™ is often filled nearly completely for proper culture conditions. The HYPERFlask™ contains ten cell culture chambers with 172 cm2 culture surfaces in the space and general shape of a traditional 175 cm2 flask. In such a system, the lower chambers are subjected to increased hydrostatic pressure relative to the upper chambers. Increasing the number of cell culture chambers in such a system with limited or no headspace would further increase hydrostatic pressure in the lower cell culture chambers, which may be undesirable. However, it may be desirable from an efficiency perspective, in terms of time and space, to increase the number of cell culture layers in such systems.